Marine organisms include plants anchored to shallow-water sea floors, plus deeper-water plants that float on the current. Zooplankton animals, such as jellyfish, float through the water because they cannot propel themselves. Nekton-classified animals swim freely, and include species such as fish and whales. Benthos animals live on the sea floor, and include lobsters and starfish. Each marine organism has developed adaptations or special features that help it thrive in its environment.
Marine creatures’ physical attributes help them adapt to their specific environments. For example, heavily built seaweed fronds resist wave damage while anchoring themselves to reefs and rocks. Warm-blooded migrating whales swim through tropical, temperate and cold waters. The whales maintain a constant body temperature, which helps them adapt to changes in the water around them. An octopus’s six arms and two legs, each with full-length suckers, allow it to grasp its prey and anchor itself to underwater rocks.
Coloration and Camouflage
Color adaptations allow marine creatures to visually melt into their surroundings, which decreases the chances that predators can see them. For example, colorful coral reef fish sport the same brilliant hues as the sunlit reefs through which they swim. Other fish use a camouflage adaptation to closely mimic their surroundings. Striped fish often swim in underwater weeds. Other creatures change their colorations as they swim through differently colored environments.
Many marine organisms have adaptations designed to defend them from predators. For example, surgeon fish have a sharp tail spine that injures its predators. Trigger fish erect a dorsal spine that helps wedge themselves into rock and reef cracks, making it difficult for predators to pry the fish out. Puffer fish swallow large amounts of water when threatened, which inflates sharp spines all over their bodies. This discourages predators that viewed the puffer fish as an easy meal.
Deep-sea creatures have developed unusual adaptations that help them survive in this inhospitable environment. The tripod fish has three fins that suspend it over mud-like deep sea floors. Brittle stars use their long, flexible arms to skim across the muck. Some deep-sea fish use bioluminescence to attract mates or prey in the darkness. Some bioluminescence is produced by bacteria living on the fish, and other fish produce their own light internally.